The present invention relates to a method and device for determining a distance on the basis of measuring the time of travel of gamma radiation.
In the metal industry there are problems of range-finding related to the surface level in ore reduction furnaces; these problems are complicated by the corroding and hot flue gases present in the range-finding space. The object of the present invention is to eliminate these problems.
Among the range-finding methods currently used in industry, the method according to the present invention is in principle similar to pulsed time-of-flight laser range-finding, in which the time of travel of light is used for range-finding. Owing to the limitations associated with the use of the laser, it cannot be used in all range-finding applications. The most significant of the limitations is perhaps the requirement of visual contact with the target to be measured by the laser beam. For this reason, for example, smoke, gases, dust, etc., prevent range-finding or hamper it. Another difficulty in the use of the laser appears in the measuring of targets having a high temperature, which increases noise in the measuring receiver and thereby increases imprecision in the measurement. On the other hand, imprecision increases because the propagation speed of light changes when the temperature of the medium changes. However, in industry there are numerous range-finding targets of the type mentioned above, and therefore it is necessary to develop other possible range-finding methods.